Jasmonates are a family of plant stress hormones, derived from linolenic acid by the octadecanoid pathway, which are found in minute quantities in many edible plants. Stress hormones such as the jasmonate family have evolved in plants, and are released in such times of stress such as extreme UV radiation, osmotic shock, heat shock and pathogen attack, to initiate various cascades which end in appropriate responses. Examples of members of the jasmonate family are jasmonic acid, which is crucial to intracellular signaling in response to injury, and methyl jasmonate, which causes induction of a proteinase inhibitor that accumulates at low concentrations in response to wounding or pathogenic attacks. Use of jasmonates for the treatment of mammalian cancer has been disclosed in U.S. Pat. No. 6,469,061, the contents of which are incorporated by reference in their entirety. In U.S. Pat. No. 6,469,061, it was shown that jasmonates were directly cytotoxic for various types of human cancer cells derived from breast, prostate, skin and blood cancers. While jasmonates elicited death in human leukemic Molt-4 cells, they did not damage normal lymphocytes.
In U.S. Pat. No. 6,469,061, one jasmonate compound in particular, methyl jasmonate, was shown to be effective in preventing development of lymphomas in mice. See also Fingrut, O. and E. Flescher. 2002. “Plant stress hormones suppress the proliferation and induce apoptosis in human cancer cells”, Leukemia 16: 608-616 (2002).
Subsequent data collected similarly showed that jasmonates do not damage healthy erythrocytes (see WO 02/080890, the contents of which are incorporated by reference in their entirety).
PCT International Patent Publication WO 2005/054172 discloses novel halogenated jasmonate derivatives, pharmaceutical compositions comprising the derivatives, and their use for reducing cancer cell growth and for treating cancer.
Jasmonic acids conjugated via the carboxyl group to amino acids occur in nature (Plant Hormones, Davies P J, ed., Kluwer Academic Publishers, London, 2004, pp. 618, 620). Several jasmonic acid-amino acid conjugates have been synthetically prepared. The amino acids include glycine, alanine, valine, leucine and isoleucine. (Jikumaru Y. et al. Biosci. Biotechnol. Biochem. 68, 1461-1466, 2004).
The pharmacological activity of jasmonate compounds makes them attractive candidates as therapeutic agents for the treatment of cancer. Only very few jasmonate derivatives have been reported in the art (see, for example, Ishii et al., Leukemia, 1-7 (2004); Seto et al. Biochem. Biosc. & Biotech. 63(2), (1999); Hossain et al. Biochem. Biosci. & Biotech. 68(9), 1842, (2004)). An unmet need exists to develop jasmonate derivative compounds that are potent chemotherapeutic drugs, with a high degree of specificity towards malignant cells.